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Independents' Day

Criticism of thiomersal in flu vaccine is unjustified

I was astonished to read Pulse's letter of the week by Dr Jerry Thompson regarding thiomersal (or, in the US, thimerosal) in the swine flu vaccine ('It's reckless to use thiomersal in the swine flu vaccine').

His view is very much a minority one, based on Andrew Wakefield's discredited research. His letter contains all the hallmarks of the antivaccine agenda, cherry-picking falsified and flawed research data, meanwhile ignoring the mountains of research material that disagree with his view.

He quotes the US Centers for Disease Control, (CDC) and yet ignores its current statement on thiomersal in swine flu vaccine:

‘No scientific evidence indicates that thimerosal in vaccines, including influenza vaccines, is a cause of adverse events other than occasional local hypersensitivity reactions in vaccine recipients. In addition, no scientific evidence exists that thimerosal-containing vaccines are a cause of adverse events among children born to women who received vaccine during pregnancy. The weight of accumulating evidence does not suggest an increased risk for neurodevelopment disorders from exposure to thimerosal-containing vaccines.'

As for the 2006 Geier research quoted by Dr Thompson, which suggested a link between the use of thiomersal in vaccines and a rise in autism cases, this work has been widely criticised. The Institute of Medicines' review of vaccine safety in 2004 described it as seriously flawed and ‘uninterpretable'. Furthermore, Dr Geier's credibility in as an expert witness has been questioned in several court cases, with a judge in 2003 branding his testimony ‘intellectually dishonest' and ‘wholly unqualified'.

It is true that thiomersal has been removed from childhood vaccines in the US. However, this is not based upon scientific theory as Dr Thompson suggests, but rather the public anxiety generated by the antivaccine movement. In fact the CDC's reason for removing thiomersal was far more pragmatic:

‘Continuing public concern about exposure to mercury in vaccines has been viewed as a potential barrier to achieving higher vaccine coverage levels and reducing the burden of vaccine-preventable diseases.'

In effect the CDC was forced to remove thiomersal because of fears that uptake rates would be affected. Follow-up studies have shown that removing thiomersal from childhood vaccines has had absolutely no effect on the rate of autism in the US, which should have ended this debate.

Unfortunately this misinformation continues to be publicised, which makes the prominence of this letter in Pulse all the more frustrating.

As GPs we should be our patient's advocates, and base our advice on the best available evidence. Spreading misinformation at this critical time from a position of such responsibility is not only highly irresponsible, but has potentially fatal consequences. As the CDC states:

‘The risks for severe illness from influenza virus infection are elevated among both young children and pregnant women, and vaccination has been demonstrated to reduce the risk for severe influenza illness and subsequent medical complications. In contrast, no scientifically conclusive evidence has demonstrated harm from exposure to vaccine containing thimerosal preservative.'

From Dr Selva Rasaiah, Cheshire

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